But the company stated that the underlying pre-tax profit was £22.1m when exceptional items, such as operating losses of £2.1m from discontinuing operations, were taken into account.
Turnover from the group's continuing operations was £557.4m, a slight fall from £562.1m last year. In spite of this, the board decided to increase the interim payment to shareholders by 5% to 4.2p.
Interserve chairman Mike Bottjer said the company's record workload of £3.9bn boded well for the future.
He said: "We have achieved a great deal of success in the first six months of 2003 in winning important new contracts in both the public and private sectors.
"As a result, our forward order book now stands at a record level, which represents a significant future revenue stream and is a strong indicator that we are well positioned for long-term growth."
The order book has been boosted by the announcement this week that Interserve has been chosen by NHS Estates along with 11 other contractors to work on the £7bn Procure 21 project.
This framework agreement covers all non-PFI construction projects with a capital cost greater than £1m.